Libyan protesters demonstrate against the militias that refuse to disarm two years after ousting Gaddafi from power. (Reuters)

Tripoli's local council called a three-day general strike after the killings in protest at the presence of militant groups in the capital. Many shops and schools across the city are currently closed and several roadblocks have been erected by local residents and armed groups.

Libya's government is struggling to maintain order in the city as hardline Islamists and rival militias refuse to disarm two years after helping to oust former Libyan leader Colonel Muammar Gaddafi from power.

In October, Libyan Prime Minister Ali Zeidan was kidnapped from his hotel in Tripoli by a former rebel militia loosely allied to the government, and held for several hours.

In a televised address to the nation, Zeidan said his brief abduction was an "attempted coup" and blamed his political opponents for the attack.